Why is it better to use a lead controller than a PD controller?

From Murray Wiki
Revision as of 01:19, 3 December 2007 by Franco (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigationJump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

The lead controller helps us in two ways: it can increase the gain of the open loop transfer function, and also the phase margin in a certain frequency range. But why could we not use just a PD controller, that increases the phase over a wider range of frequencies?

The use of the derivative action should always be limited: it helps improve the control performance when the error signal changes rapidly, but for the same reason it could amplify unwanted disturbances on the measured output.

--Elisa